/* An example to illustrate the use of virtual specifier For Q/A: https://www.sololearn.com/Discuss/814374/virtual */ #include #include using namespace std; class Figure { public: /* Try commenting out the virtual method and uncommenting the non-virtual one. See the result. */ /* Declaring a pure virtual draw() method, as we can't draw a GENERIC shape */ virtual void draw() = 0; /* Non virtual method. Has no sense and will not work as it should. Adding 'virtual' before the declaration will solve the case, but still, no point in drawing an unknown shape */ //void draw() {cout << "Drawing some nonsense for 'a' shape" << endl;} }; class Rectangle : public Figure { public: void draw() { cout << "Rectangle was drawn" << endl; } }; class Triangle : public Figure { public: void draw() { cout << "Triangle was drawn" << endl; } }; class Hexagon : public Figure { public: void draw() { cout << "Hexagon was drawn" << endl; } }; int main() { Figure *shapes[10]; /* Populate array with random shapes */ for (int i=0; i < (sizeof(shapes)/sizeof(shapes[0])); i++) { int shapeType = rand() % 3; switch (shapeType) { case 0: shapes[i] = new Rectangle(); break; case 1: shapes[i] = new Triangle(); break; case 2: shapes[i] = new Hexagon(); break; } } /* Draw every shape in the array. We don't know what shapes are there */ for (int i=0; i < (sizeof(shapes)/sizeof(shapes[0])); i++) { shapes[i]->draw(); } /* Cleanup */ for (int i=0; i < (sizeof(shapes)/sizeof(shapes[0])); i++) { delete shapes[i]; } return 0; }

Q/A Virtual specifier example